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I don't know what type of the mistake it was.
It's difficult to ask somebody, the book was published in 1973.:)
Possibly, translation.

Possibly, there is a problem with translation from German - Joh. Abr. Herder & Sne. (But this company name was in the first part of 19th century).

Possibly. But if several different sources have the similar info, it's possible to get the information near the true.

At the beginning of the thread, the razor is #78.
Here is the scan from...

I don't know about what sources you speak.:)
That info from my books, including Sword and Bayonet makers of Imperial Germany.

Yes.
http://straightrazorpalace.com/razors/76945-r-herder-6-8-full-hollow-solingen.html#post879678

http://straightrazorpalace.com/razors/75376-need-information-6-8-f-herder-acquisition.html#post859908